Add ComparisonPlace.

[jdcove2]

This PR adds ComparisonPlace. ComparisonPlace runs the configured two places and gives them identical IBDO's. ComparisonPlace then compares the output of the two places and logs any differences.

[cfkoehler]

@jdcove2 why is this label as 'test-only' when this is a new place and feature.
I would have expected to see this labeled as 'feature'. Probably something that will never be run on a production system but still doing more then just creating/modifying java test code.

Happy to be proven wrong. I have not fully digested this PR yet.

[jdcove2]

"Typo" -- I will remove it.

[drivenflywheel]

Minor changes requested

[drivenflywheel]

Need to rebase. Unit tests in this PR were broken by PR #664, and merging this PR in its current state will prevent master from building.

[rpg36]

Approving, but bringing up the concern that this place will introduce invisible places. So it might conflict with the work that was done recently to address invisible places.

[jdcove2]

I plan to put up another PR to address the "invisible place" issue once this one is merged. Since this place should never be used except locally or on a development system, approving and merging it should not cause any problems.